This invention relates to loop material, particularly to material to be engaged with hooking members to form a fastening, and to its manufacture and use.
In the production of woven and non-woven materials, it is common to form the material as a continuous web that is subsequently spooled. In woven and knit loop materials, loop-forming filaments or yarns are included in the structure of a fabric to form upstanding loops for engaging hooks. As hook-and-loop fasteners find broader ranges of application, especially in inexpensive, disposable products, some forms of non-woven materials have been suggested to serve as a loop material to reduce the cost and weight of the loop product while providing adequate closure performance in terms of peel and shear strength. Nevertheless, cost of the loop component has remained a major factor limiting the extent of use of hook and loop fasteners.
We have realized that non-woven fabrics constructed with certain structural features are capable of functioning well for their intended purpose as hook-engageable loop fabrics, while providing particular advantage in regard to expense of manufacture and other properties.
According to one aspect of the invention, a loop product for hook-and-loop fastening is provided, the loop product comprising a non-woven, uncompressed and unshrunk web of entangled fibers of substantial tenacity and of uniform fiber composition, the fibers forming both a sheet-form, web body and hook-engageable, free-standing loops extending from the web body, the product having a basis weight of less than about 2 ounces per square yard. xe2x80x9cUniform fiber compositionxe2x80x9d as used here includes a loop-forming fiber blend that is uniform, i.e. not formed by layers of two different types.
Preferred products according to this aspect of the invention have one or more of the following features.
The loop product has an overall thickness, including the web body and a majority of the loops, of less than about 0.150 inch, in many instances preferably less than about 0.100 inch.
The loops extend from associated entanglements within the main web body to an average loop height, measured as the perpendicular distance from the web body, from their associated entanglements, of between about 0.020 and 0.060 inch, preferably, in many instances the average loop height being between about 0.5 and 0.6 times the overall thickness of the product.
Another aspect of the invention, is a hook-engageable loop fabric if basis weight less than 4 ounces per square yard having all of the above features, but without regard to whether the fabric is made of fibers of uniform composition.
In either case, in preferred embodiments, the web body is stabilized in a stretched condition, the web body including knots formed by tightened fiber entanglements.
In preferred cases of each of these aspects of the invention, the web body is stabilized in a condition of at least 20 percent a real stretch, and in certain of these cases the web body is stabilized in a condition of at least 10 percent stretch in each of two perpendicular directions. In certain important cases the knot density is between about 50 and 1000 knots per square inch of web body.
Preferably the fibers generally have a tenacity of at least 2.8 grams per denier; in many instances the fibers generally have a tenacity of at least 5 grams per denier, and in certain important instances the fibers generally have a tenacity of at least 8 grams per denier.
The loops preferably extend from the web body to varied heights to form a multi-level arrangement of hook-engageable loops.
The web is preferably stabilized in a stretched condition, the web body including knots formed by tightened web entanglements, the loops extending from loop structures, at least some of the loop structures each comprising a common, elongated trunk portion extending from the web from an associated knot, and multiple loops extend from the trunk portion.
The fibers are preferably of a material selected from the group consisting of polyester, polyurethane, polypropylene, polyethylene and nylon, homopolymers, mixtures, copolymers, alloys, or coextrusions thereof, and natural fibers. In certain presently preferred cases the fibers are polyester.
The loop product preferably has a Gurley stiffness of less than about 300 milligrams.
The loop product preferably comprises a binder selected from the group consisting of acrylics, urethanes, polyvinyls, formaldehydes, glyoxals and epoxies.
In other cases the loop product preferably comprises polymer filaments entangled among fibers of substantial tenacity the filaments being at least partially melted to bond the web body.
According to another aspect of the invention, a non-woven loop fabric for engaging hooks in a hook-and-loop fastener is provided, the fabric having a basis weight of less than about 2 ounces per square yard and comprising a stretched, non-woven mat of fibers entangled at knots therein, the mat having a front side and free-standing and spaced-apart loop structures extending at least from the front side of the mat from the knots in the mat, these structures defining hook-engageable loops and corresponding associated knots.
Preferred products according to this aspect have one or more of the following features.
The mat of the loop fabric is stabilized in a condition of at least about 20 percent areal stretch, in important instances the mat is stabilized in a condition of at least 50 percent areal stretch, and in many instances preferably the mat is stabilized in a condition of at least 100 percent areal stretch. A presently preferred range is 75 percent to 150 percent.
The mat is stabilized in a condition of at least 10 percent stretch in each of two perpendicular directions, in many instances the mat is stabilized in a condition of at least 25 percent stretch in each of two perpendicular directions.
At least some of the knots of the mat are secured to resist relative fiber motion and further stretching of the fabric, preferably the loop fabric further comprising a binder to secure the fibers of the loop structures at their associated knots, in many instances the loop fabric comprising between about 20 and 40 percent binder, by weight, in many preferred instances the fabric being about one third by weight of binder.
In preferred cases the binder is selected from the group consisting of acrylics, urethanes, polyvinyls, formaldehydes, glyoxals and epoxies. In other cases the binder comprises polymer filaments entangled among the fibers, the filaments being at least partially melted to encapsulate the knots, and set. In certain cases the binder forms a backing adapted to be welded to a substrate, and in certain cases the binder forms an impermeable barrier. In certain cases the binder comprises a fire-retardant material.
At least some of the loop structures of the loop fabric each comprise multiple loops emanating from a common fiber knot.
Similarly to the first mentioned aspects of the invention, in implementations of the present aspect of the present invention the loop fabric preferably has an overall thickness, including the mat and a majority of the loop structures, of less than about 0.150 inch.
Likewise, the loop fabric preferably has loops that extend to an average loop height from their associated entanglements, measured as the perpendicular distance from the mat, of between about 0.020 and 0.060 inch and, preferably in many instances the average loop height is between about 0.5 and 0.6 times the overall thickness of the fabric.
In preferred cases, the knot density of the loop fabric is between about 50 and 1000 knots per square inch of mat, in certain preferred cases the knot density being between about 100 and 600 knots per square inch of mat, and in particularly important cases the knot density being between about 150 and 300 knots per square inch of mat.
In preferred cases, the fibers generally have a tenacity of at least 2.8 grams per denier, in particular cases the fibers generally have a tenacity of at least 5 grams per denier and in other cases the fibers generally have a tenacity of at least 8 grams per denier.
In preferred cases the loops of the loop structures extend from the mat to varied heights to form a multi-level arrangement of hook-engageable loops.
In preferred cases at least some of the loop structures each comprise a common, elongated trunk portion extending from the mat from an associated knot and multiple loops extend from the trunk portion.
Also in preferred cases the loop structures generally each comprise three or more hook-engageable loops.
In preferred cases the fibers are generally of 15 denier or less; while in particular cases the fibers are generally of 8 denier or less.
In important implementations of this aspect of the invention the fibers are crimped at a crimp density of at least about 7 crimps per inch, the fibers are of a material selected from the group consisting of polyester, polyurethane, polypropylene, polyethylene, nylon, and homopolymers, mixtures, copolymers, alloys, and coextrusions thereof and natural fibers and the loop fabric has a Gurley stiffness of less than about 300 milligrams; in important cases the loop fabric has a Gurley stiffness of less than about 100 milligrams.
According to another aspect of the invention a loop product for hook-and-loop fastening is provided, comprising a stretched, non-woven fabric of entangled fibers having front and back surfaces, the front surface having exposed, through-forced loops of the fibers extending therefrom, capable of being engaged by hook-type fasteners, and a binder securing the fibers at the back surface of the fabric to resist further elongation of the fabric.
According to another aspect of the invention a loop product for hook-and-loop fastening is provided, comprising a stretched, non-woven fabric of entangled fibers having front and back surfaces, the front and back surfaces having exposed, through-forced loops of said fiber extending therefrom, capable of being engaged by hook-type fasteners, and a binder securing the fibers to resist further elongation of the fabric.
According to another aspect of the invention a hookand-loop fastener is provided, comprising a loop product according to any of the preceding aspects of the invention, preferably with one or more of the further described features, and a hook portion preferably of molded construction, having an array of hooking elements extending from a sheet-form base, the hooking elements constructed to engage the hook-engageable loops of the loop product to form a releasable fastening.
In preferred cases of this aspect the hook-and-loop fastener has an overall thickness, engaged and at rest, of about 0.075 inch or less, and in certain preferred cases the hook-and-loop fastener has an overall thickness, engaged and at rest, of about 0.050 inch or less.
According to another aspect of the invention a substrate is provided comprising a surface layer of thermoplastic material and the loop product accordingly to any of the above-mentioned aspects, preferably with one or more of the further described features, at least some of the fibers of the fabric of the loop product opposite the hook-engageable loops being encapsulated within the layer of thermoplastic material, for instance by use of the techniques described in U.S. Pat. No. 5,518,795, which is hereby incorporated by reference as if it were fully set forth herein.
Another aspect of the invention is a package comprising a first closure portion comprising the loop product of any of the above mentioned aspects of the invention and a second closure portion having a hook product, preferably of molded plastic form, comprising an array of hooking elements extending from a sheet-form base, the hooking elements constructed to engage the extended loops of the loop product to hold the package in a closed or open position.
In preferred cases the loop product and the hook product of the package have a combined overall thickness, engaged and at rest, of less than about 0.075 inch.
Another aspect of the invention is a disposable article of clothing comprising the loop product of any of the above described aspects and features arranged to extensively cover a portion of a wearer""s body or presented on a panel or tab that has been secured to the article of clothing as by pressure sensitive adhesive, and a fastener with hooking elements is arranged to engage the loops of the fabric, panel or tab to form a releasable fastening to retain the article of clothing on a wearer.
In preferred cases, the disposable article of clothing comprises a surgical gown, in other cases a diaper and in these or other cases the fabric comprises a binder forming a water-resistant or water impermeable liner.
In still another product aspect of the invention an air filter is provided comprising the loop product of any of the foregoing aspects and preferred features constructed to be mounted and act to intercept and filter a flow of air.
By xe2x80x9chook-engageablexe2x80x9d and similar terms used above and throughout this specification, we mean that the loop material defines openings of size adequate to receive the tip or head portion of a male fastener element (such as a hook-shape or mushroom-shape element, for instance) for forming a fastening.
By the word xe2x80x9centanglementsxe2x80x9d we mean the nodes at which a multiplicity of fibers are intertwined in the non-woven web. These entanglements may be relatively loose, as formed directly by a needling process, for instance, or tightened after formation of the entanglements. By the word xe2x80x9cknotsxe2x80x9d we mean entanglements that have been tightened by applying tension to their intertwined fibers in at least one direction in the plane of the web, and remain in an at least partially tightened state.
We have also realized that such loop fabrics as just described are advantageously produced by employing certain manufacturing techniques and methods.
An important aspect of the invention is a method of forming a loop product for a hook-and-loop fastener, the method comprising the steps of forming a batt of loose, staple fibers, entangling the fibers to produce a non-woven fabric of fibers joined at entanglements, with loops of some of the fibers extending from at least one side of the fabric, subsequently stretching the fabric to tighten the entanglements to form knots, and binding the knots to hold the fabric in its stretched state.
Another important aspect of the invention is a method of forming a loop product for a hook-and-loop fastener, the method comprising the steps of forming a batt of loose, staple fibers; forcing some of said fibers through the batt, thereby entangling the fibers to produce a non-woven fabric of fibers joined at entanglements, and also thereby forming fibrous loops extending from one side of the fabric, coating at least some of the entanglements of the fabric with a binder, and subsequently stretching the fabric to tighten the entanglements to form knots, the binder adapted to hold the fabric in its stretched state.
One or more of the following features can be employed to advantage with methods according to either of the aspects of the invention just described.
The batt is through-punched with needles.
The fibers are forced through the batt for entangling the fibers by needling the batt a first time with a needle-punching density of at least 100 punches per square inch, and needling the batt a second time with a greater needle-punching density. The batt is preferably needled a final time with a needle-punching density of between about 1200 and 1600 punches per square inch.
The batt is needled a first time in a first direction, and needled a subsequent time in a second direction, the second direction being opposite the first direction. In preferred cases, the batt is needled a first time and a second time in a first direction and needled a third time in the second direction.
The method includes setting a binder to stiffen the knots of the stretched fabric.
The fabric is stretched by at least 15 percent in a cross-machine direction.
The fabric is stretched to increase its area by at least about 20 percent, in certain preferred cases the fabric is stretched to increase its area by at least about 50 percent, and in particular cases the fabric is stretched to increase its area by at least about 100 percent.
The step of about stretching produces a fabric with a width of at least five feet, or even much more.
The method includes the step of brushing the loops to disentangle loosely-held loop fibers.
According to still another aspect of the invention a method of forming a loop component of a hook and loop fastener is provided comprising forming a stretchable non-woven fabric comprised of entangled fibers, some of the fibers forming hook-engageable loops that extend from the entanglements, thereafter stretching the thus formed web thereby tightening at least some of the entanglements into knots, and thereafter binding the stretched fabric to give it stability.
The invention can provide a very inexpensive loop product which can very effectively engage and retain hooks, such as in hook-and-loop fasteners. The loop product can be particularly useful in combination with extremely small, inexpensive molded hooks as fasteners for disposable products, such as diapers, medical devices or packaging.